Ultra Quiet Suction System with Improved Lifespan

Description

CROSS REFERENCE TO RELATED PUBLICATIONS

This application claims priority from U.S. Provisional Patent Application Ser. No. 63/711,332, entitled “Ultra Quiet Suction System with Improved Lifespan”, filed on 24 Oct. 2024, which is hereby incorporated by reference as if set forth in full in this application for all purposes.

FIELD OF THE INVENTION

The present invention relates to improving pump system performance, in terms of quietness and lifespan. More specifically, certain embodiments of the invention are particularly relevant to improving small portable systems that may be used in health care settings or at home.

BACKGROUND OF THE INVENTION

Currently available suction systems are generally very noisy, generating sound levels on the order of 60 dB or more. This is generally undesirable, especially if the systems have to be operated for long periods of time, close to the user and other people in the vicinity. The system noise is primarily generated when the air (or other gaseous medium) exhausted by the pump motor moves turbulently around the space surrounding the motor within the pump housing and finally exits the housing at one or more vents. A secondary contribution to system noise is generated by the motor itself, the loudness of that noise partly depending on the drive voltage—the higher the voltage driving a pump motor, the noisier the motor is generally found to be.

Another issue with currently available suction systems is that their lifespans are undesirably low, particularly if they are operated continuously. 2000 hours total running time is a typical limit quoted by the manufacturers, even if that value does not include periods in which the system is run continuously for over 24 hours. In some cases, continuous run times of no longer than 1 hour per session are advised. These limits are determined in large part because of the heat generated by the pump motors. This heat directly or indirectly limits motor lifetime, which in turn can impact system lifetime and the cost of replacement and/or the cost of maintenance of that motor.

It should be noted that the motor's drive voltage directly determines the motor's torque, which also correlates to wear and tear of the motor and other parts, which in turn may influence system lifetime. So, if adequate suction power can be achieved while running a motor at a significantly lower voltage than its maximum rating, this is desirable from the viewpoint of improving lifetime, as well as reducing heat and noise.

A typical prior art suction system, particularly if required to be small and portable, uses a DC power supply enclosed within or even integrated into the system housing. This supply provides DC power to drive the DC motor that generates the suction power required by the application of interest. The power supply may be a battery, or it may be an AC to DC converter connected to external mains (utility) AC power. In either case, some heat is generated as a by-product at the battery or converter, which can raise the temperature of the motor and other components enclosed in the same system housing, and in turn that temperature rise can impact system lifetime. While brushless DC motors can achieve high efficiency (generating less heat than standard DC motors that depend on direct-contact motor commutators) they require special drive circuitry and generally are also fed by AC-DC converters within or integrated into the system housings.

Some other prior art suction systems use AC motor units rather than DC ones, but they incur the disadvantage of generating even more heat than comparable DC motors.

There is therefore a need for improved suction systems that are designed to generate less noise and/or less heat than current systems, while still maintaining adequate suction for the application of interest. Ideally both of these goals would be achieved in a single system that provides a quiet and long-lived product, though different applications may have a greater need for one benefit than the other.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 (Prior Art) is a block diagram illustration of a prior art suction system.

FIG. 2 is a block diagram illustration of a suction system according to some embodiments of the present invention.

FIG. 3 illustrates a prototype silencer 380 and associated parts for some embodiments of the present invention.

FIG. 4 illustrates a measurement set up used for comparing one embodiment of the present invention with a prior art system.

FIG. 5 is a block diagram illustration of a suction system according to some embodiments of the present invention.

FIG. 6 illustrates a view of a partly assembled prototype system according to some embodiments of the present invention.

FIG. 7 illustrates a view of a partly assembled prototype system of essentially the same type as that shown in FIG. 6, but at a later stage of assembly.

DETAILED DESCRIPTION

Described herein are embodiments of a suction system in which noise performance and system longevity are improved relative to currently available suction systems. More specifically, embodiments of the invention provide systems with low noise and/or longer expected lifetimes by making use of one or more of the approaches described below.

FIG. 1 illustrates a typical prior art suction system 100 in block diagram form. System 100 includes a housing 110 defining an enclosure for a DC motor 120 driven by power delivered from unit 130 (see filled arrow A). In the illustrated case, unit 130 takes the form of an AC-DC converter, which may make up a switching power supply. The converter's input is AC power supplied (see hollow arrow B) from an external unshown source, such as mains (utility) power. In other cases (not shown) unit 130 may be a battery, charged by an external AC power source. The charging could be carried out before and/or during the time the system is run. In other cases, unit 130 may be a battery. In any case, the presence of the converter or battery within the system housing constitutes an undesirable source of heat, adding to the heat generated by the motor 120 itself during its normal operation.

When motor 120 is running, air (or another gaseous medium) is drawn from an external volume of interest into the motor through inlet tubing 140 and expelled as exhaust gas through outlet 150 into the space enclosed by system housing 110. Inlet tubing 140 would be connected at one end (the upper end in the orientation of the figure) to the external chamber of interest being pumped, that chamber being omitted from the figure for simplicity. The exhaust from motor 120 is pushed into the space within the housing where it can travel around to potentially fill that space, as indicated by the curved dashed arrows, until it finally makes its way out of the housing at vent 160. As mentioned above, such air flow, forced around various objects within the housing and then emerging through a vent, generates sound, which is generally perceived by the user and others in the vicinity as unwanted noise.

FIG. 2 is a block diagram illustration of a suction system 200 according to some embodiments of the present invention. System 200 differs from prior art system 100 by including some inventive features aimed directly at either reducing noise or increasing system longevity, or both.

The system achieves noise reduction primarily by including a noise silencing element 280 and a modified tubing arrangement by which although inlet tubing 240 serves the same function as tubing 140 in FIG. 1, another length of tubing 255 feeds the gas exhausted from motor 220 into noise silencing element 280, instead of that exhaust being released to fill the interior of the housing. Then, after passing through that silencing element (which may be called e.g. a silencer, a noise suppressor, or a muffler) the exhaust leaves system housing 210 through vent 260, guided there by another length of tubing 286. The interior structure of silencer 280 is not shown in the figure. In some embodiments, silencer 280 may include one long serpentine channel (unshown) through which the exhaust travels. In other embodiments, the silencer may include a plurality of channels, straight or curved, through which portions of the exhaust make their way, splitting and recombining (see FIG. 3). In yet other embodiments, there may be small cavities within which portions of the exhaust may circulate during their passage. In some embodiments, the silencer may include a combination of shaped elements of the same or different types, interacting with the exhaust gas to dissipate or cancel sound waves as the gas passes through the silencer on its way to emerge through the vent to the exterior. The term “labyrinth structure” may be used to refer to any arrangement of one or more shaped elements configured to dissipate or cancel sound waves as gas moves through that structure.

In some embodiments, not shown, silencer 280 may be positioned directly against or integrated into a boundary surface of housing 210 that includes vent 260, so there is no need for tubing 286 to carry the exhaust between the silencer and the vent. In other embodiments, not shown, the gas may pass from the silencer into an intervening chamber which is positioned directly against or integrated into a wall of the housing, and then finally exit the system through a vent in that wall. In any of these embodiments, there may be more than one vent. Experiments with an “intervening chamber with two vents” embodiment have shown the potential to reduce sound even more effectively than with the simpler tube-to-vent arrangement shown in FIG. 2.

In some embodiments of the present invention, an additional reduction in noise may be achieved if pump 220 is selected to be a dual diaphragm pump, allowing the pump motor to provide a comparable suction rate to that of a standard single diaphragm pump but using just half the drive voltage that would be required by the motor in that single diaphragm pump. This lower voltage in turn may also improve overall system lifetime, as mentioned in the Background section of this disclosure. FIGS. 6 and 7, discussed below in further detail, show embodiments that include such a dual diaphragm pump.

Another significant feature of system 200, distinguishing it from prior art systems like that shown in FIG. 1, is that it dispenses with any DC power supply within the system housing, instead relying on a connection (see dark arrow) to an external DC source. In some embodiments the source may be a battery (not shown) positioned outside the housing, or attached to the exterior of the housing; in other embodiments, the DC power may be derived from mains power converted to DC outside the housing by an AC to DC converter. In yet other embodiments, a USB adapter may be used as a particularly convenient means to provide the necessary DC power at a suitable voltage from an external AC or DC source. In all these embodiments, the components within system 200 are not subjected to the heat that is inevitably generated in power handling elements, such as AC to DC converters or batteries, as they would have been in prior art systems.

FIG. 3 shows 3D renderings of an exemplary silencer 380 and associated parts for some embodiments of the present invention. View A shows the assembled silencer 380, with input and output ports 382. View B is an internal view of one type of channel assembly 384 that could be present within such a silencer, to guide the flow of exhaust passing through and suppress or even “silence” the associated noise to an appreciable extent. Other silencer types in other embodiments may include other interior features as discussed above. View C shows part of the base of a suction system housing 310 having a depression or cavity 312 shaped and sized such that silencer 380 can fit neatly into it and then fastened into place. In other embodiments instead of having a depression configured to fit the silencer, the silencer may be attached directly against the housing floor or wall by some other standard fastening means, or even integrated directly in the housing walls. View D shows silencer 380 securely fastened into the depression in the floor of housing 310. It should be noted that silencer 380 is a passive device, performing its function without requiring any electrical power input. Any or all of the parts shown in FIG. 3 may be plastic parts, fabricated using well-established inexpensive molding techniques, and contributing to a relatively lightweight hence portable system.

Experiments with prototype suction systems including silencers such as those shown in FIG. 3 have demonstrated impressively low noise output, especially in embodiments in which the pump motor is driven at half the manufacturer specification voltage, and even more so when the pump is a dual diaphragm pump. Noise values have been demonstrated at or below 40 dB, measured a few inches away from the systems, using some of the most recent designs. These noise levels are barely audible in a very quiet room (typically having an ambient noise level of 35 dB). Noise values measured under the same conditions for commercial competitors' suction systems were in the 45 dB to 46 dB range, even though the latter systems were providing half the suction rate of the prototypes. The set up used for obtaining these measurements is shown in FIG. 4, with a commercial sound level meter positioned midway between the two portable suction systems being compared, a prior art suction system 400A and a suction system embodiment of the present invention 400B.

FIG. 5 illustrates a suction system according to embodiments of the present invention that are similar to those of FIG. 2 but include other advantageous features aimed at increasing system lifetime by deliberately cooling the pump motor during operation. In system 500, inlet tubing 540 directs the air or other gas drawn by and through pump motor 520 into a hollow coil 590 wrapped around pump motor 520. The coil is typically made of a material with high thermal conductivity, such as copper or aluminum, and is wrapped around the motor to try to make good thermal contact with the motor's outer surface. The air or other gas being drawn by the pump from its target is typically at room temperature, so as it is pumped through coil 590 during motor operation, it absorbs some of the heat being generated by the motor, cooling the motor, which in turn minimizes the temperature rise experienced by other nearby system components. The dash-outlined arrows in the figure illustrate the gas flow path, first passing from tubing 540 through the pump motor interior chamber, next through tubing 552 into the cooling coil 590 wrapped around the motor, and then, as in the embodiments discussed above, passing through a length of outlet tubing 555 into a silencer 580, and finally passing from the silencer to reach vent 560 and exit the housing 510, either through a short tube 586 as shown, or in other unshown cases, or via an intervening chamber or a direct vent from the silencer, as discussed above.

In the system of FIG. 5 (and in FIGS. 6 and 7 discussed below) the gas entering the system passes though the interior of the pump motor before being directed into the coil and thence to the silencer. It should be noted that in other embodiments, not shown, a tubing arrangement may be used that directs the gas entering the system to flow through the coil before it passes through the motor rather than vice versa. Essentially the same motor-cooling objective could be achieved either way.

One practical problem arising with the use of a cooling coil is that due to manufacturing limitations (fabrication tolerance and the process of winding) the cooling effect may be limited by less than perfect contact between the coil and the outer surface of the motor in some areas, lowering the efficiency of heat transfer. This problem may be addressed as shown in FIG. 6, by the application of a thermally conductive glue, typically an epoxy, to fill in the gaps between the outer surface of the motor and the overlying coil at such areas 694, where the glue is visible as light colored patches.

FIG. 6 shows a partly assembled prototype system 600 according to some embodiments of the present invention that use this coil-based approach for system cooling, but by means of a pair of coils rather than just one. The advantage of having two coils wrapped around different halves of the motor surface is a more even distribution of the cooling action of the gas over the whole length of the motor. This particular system also includes another advantageous feature mentioned above in the discussion of FIG. 3-a dual diaphragm pump motor, which not only reduces noise but also facilitates running the motor at half its nominal drive voltage while maintaining desirably high suction power.

In the illustrated case, two copper coils 690A and 690B are separately wrapped around a corresponding half of the cylindrical body portion of dual diaphragm pump motor 620. During motor operation, half of the gas drawn by the pump and passing through the motor interior flows through tubing 692A and half through 692B into the corresponding coils.

Other embodiments (not shown) may be envisaged in which the same type of conductive cooling effect may be achieved with an alternative to coils, which present difficulties for cost-effective mass production, which would be particular desirable for the type of health care applications envisaged, in institutional or home settings. Such embodiments would address the mass production issue by using a roughly cylindrical outer jacket made of a thermally conductive material such as Aluminum, or another thermally conductive material, positioned to fit closely and simply (no winding required) around the motor and connected to input and output tubing just as a coil would be. The jacket would be fabricated to include grooves, fingers and/or channels, such that the gas input into the relatively narrow concentric spaces between the jacket and the motor would not flow linearly along the length of the motor but be guided to follow a spiral path around the motor, very similar to that occurring in the coil-based embodiments. However, in these proposed embodiments there would not be any additional metal surface between the hot motor and the relatively cool air trapped by the jacket, or any gaps to be filled in with thermally conductive epoxy. In some cases, two side-by-side jackets may be used for more unform heat transfer, just as in the two coils case shown in FIG. 6.

FIG. 7 shows a partly assembled prototype system 700 according to some of the embodiments that use a dual diaphragm and dual coil approach as in system 600. More of the tubing network is visible than in FIG. 6, showing input tubing 740 directing the gas being drawn by the system first through a vacuum safety valve junction 742 that can limit suction to within a desired range (such as within −40 to −45 kPa, for example) and then a T-coupler 744 which splits the flow into left and right paths (indicated L and R) each leading to a corresponding diaphragm inlet of the dual diaphragm motor. Tubing (792A, 792B) then directs the corresponding split streams of gas leaving the motor into a corresponding coil (790A, 790B) wrapped around motor 720.

Embodiments of the present invention offer many benefits. The major benefits are the generation of dramatically lower noise levels than comparable systems of the prior art, and the expectation of significantly longer lifespans, without paying any penalty in terms of basic suction performance. One additional benefit is the confinement of the fluid being drawn into the system to tubes, chambers and confined spaces within the silencer, which reduces the risk that any liquid leaking or condensing out of the fluid being pumped will collect within the housing and make contact with any electrical components within the pump housing.

It should be appreciated that the disclosure teaches just a few examples of the illustrative embodiments, that many variations of the invention can easily be devised by those skilled in the art after reading this disclosure, and that the scope of the present invention is to be determined by the following claims.